1. Technical Field
The present invention relates especially to a blower suitable in the application for cooling office automation equipment.
2. Description of the Prior Art
Conventionally, the double row bearing device employed in the blower for cooling the office automation equipment includes a pair of ball bearings 102 and 103 fit on a shaft 101 of the motor as shown in FIG. 8.
Inner rings 102a, 103a of each ball bearing 102, 103 are loose fit to the shaft 101, and outer rings 102b, 103b are also loose fit within the sleeve 104 being the bearing housing.
A compressed coil spring 106 for applying pre-load to both ball bearings is interposed between the outer surface of the inner ring 102a of the left ball bearing 102 disposed adjacent the yoke 105 and the front face plate 105a of the yoke 105 integrally connected to the front face plate 108a of the impeller 108. A stop ring 107 for retaining the ball bearing 103 is provided around the right end of the shaft 101 and secured thereto.
However, in the case of the pre-loading means as shown in FIG. 9, the clearance defined between the yoke 105 and the ball bearing 102 is very narrow, making it difficult to incorporate the compressed spring 106 into the clearance. Further, the necessity of incorporation of the spring into the clearance upon assembling the blower will make the assembling operation complicated. The level of the pre-loading force depends exclusively upon the distance between the yoke 105 and the bearing 102. Setting such distance is difficult and therefore, applying suitable amount of pre-loading force is difficult.
The sleeve 104 has at both ends thereof larger inner diameter portions 104a, 104b for accommodating the outer rings of the ball bearings. Each of the larger inner diameter portions includes a shoulder respectively to which the outer ring of the ball bearing will be abutted. When the larger inner diameter portions 104a, 104b are more or less eccentrically formed with respect to the sleeve, the rotational movement of the shaft is also effected eccentrically, and generates vibrations or noise and therefore a precise machining on the larger inner diameter portion is required.
As it can be seen from the above, the blower employing the double row bearing device of the prior art requires a pair of ball bearings including an inner and an outer ring. A complicated operation for inserting the pre-loading spring is required. This involves a high cost for manufacturing the bearing device.
The bigger the diameter of the motor shaft is, the higher is the rigidity of the shaft, and thus the rotational run out is reduced and a quiet motor with high durability can be obtained. However, the diameter of the shaft of the bearing device of the prior art is smaller than that of the sleeve by twice the sum of the thickness of the inner and outer rings of the ball bearings fit around the shaft. Therefore, it is difficult to provide durability, prevent rotational run out, and reduce generation of vibrations or noise.
Accordingly, the object of the present invention is to provide a blower including a bearing structure wherein the number of components is reduced, assembly is easy, manufacturing cost is reduced, and the diameter of the shaft is increased being good at its durability, further eliminating rotational run out and providing superior quietness.
These and other objects are achieved by a blower in accordance with the first aspect of the present invention having an impeller adapted to be rotated upon energizing the blower comprising;
a bearing device for supporting a rotational center portion of the impeller, the bearing device including;
a sleeve,
a stepped shaft including a larger diameter portion and a reduced diameter portion provided at one end thereof,
the first inner raceway groove formed at an appropriate position around the outer peripheral surface of the larger diameter portion,
the first outer raceway groove formed on an inner peripheral surface of the sleeve so as to correspond with the first inner raceway groove,
balls of the first row interposed between the first and second grooves,
an inner ring slidably fit over the reduced diameter portion,
the second inner raceway groove formed around an outer peripheral surface of the inner ring,
the second outer raceway groove formed on the inner peripheral surface of the sleeve so as to correspond with the second inner raceway groove,
balls of the second row interposed between the second inner and outer grooves,
a stop ring provided around the inner periphery of the distal end of the reduced diameter portion, and
a pre-loading spring interposed between the stop ring and an end surface of the inner ring to provide a suitable amount of pre-loading force to the inner ring.
The blower in accordance with the second aspect of the present invention comprising;
a frame including a base connected through stays to the frame so as to be positioned at the central portion of the frame,
a cylindrical bearing holder formed integrally with the base to extend therefrom forwardly,
a stator including an iron core and a coil and mounted on the exterior of the cylindrical bearing holder,
an impeller including a front face plate, a flange formed over the outer periphery of the front face plate, and suitable numbers of blades provided on the outer periphery of the flange,
a yoke including a front face plate to which the front face plate of the impeller is secured, a flange formed over the outer periphery of the front face plate, a magnet mounted on the flange, and
a bearing device for supporting the central portion of the yoke through a shaft of the bearing device to which the central portion of the yoke is fit and secured thereto, the bearing device including;
a sleeve,
a stepped shaft including a larger diameter portion and a reduced diameter portion provided at one end thereof,
the first inner raceway groove formed at an appropriate position around the outer peripheral surface of the larger diameter portion,
the first outer raceway groove formed on an inner peripheral surface of the sleeve so as to correspond with the first inner raceway groove,
balls of the first row interposed between the first and second grooves,
an inner ring slidably fit over the reduced diameter portion,
the second inner raceway groove formed around an outer peripheral surface of the inner ring,
the second outer raceway groove formed on the inner peripheral surface of the sleeve so as to correspond with the second inner raceway groove,
balls of the second row interposed between the third and fourth grooves,
a stop ring provided around the inner periphery of the distal end of the reduced diameter portion, and
a pre-loading spring interposed between the stop ring and an end surface of the inner ring to provide a suitable amount of pre-loading force to the inner ring.
The blower in accordance with the third aspect of the present invention comprising;
a frame including a base connected through stays to the frame so as to be positioned at the central portion of the frame,
a cylindrical bearing holder formed integrally with the base to extend therefrom forwardly,
a stator including an iron core and a coil and mounted on the exterior of the cylindrical bearing holder,
an impeller including a front face plate, a flange formed over the outer periphery of the front face plate, and suitable numbers of blades provided on the outer periphery of the flange,
a yoke including a front face plate to which the front face plate of the impeller is secured, a flange formed over the outer periphery of the front face plate, a magnet mounted on the flange, and
a bearing device for supporting the central portion of the yoke through a sleeve of the bearing apparatus to which the central portion of the yoke is fit and secured thereto, the bearing device including;
a sleeve, a stepped shaft including a larger diameter portion and a reduced diameter portion provided at one end thereof,
the first inner raceway groove formed at an appropriate position around the outer peripheral surface of the larger diameter portion,
the first outer raceway groove formed on an inner peripheral surface of the sleeve so as to correspond with the first inner raceway groove,
balls of the first row interposed between the first and second grooves,
an inner ring slidably fit over the reduced diameter portion,
the second inner raceway groove formed around an outer peripheral surface of the inner ring,
the second outer raceway groove formed on the inner peripheral surface of the sleeve so as to correspond with the second inner raceway groove,
balls of the second row interposed between the third and fourth grooves,
a stop ring provided around the inner periphery of the distal end of the reduced diameter portion, and
a pre-loading spring interposed between the stop ring and an end surface of the inner ring to provide a suitable amount of pre-loading force to the inner ring.
The blower in accordance with the fourth aspect of the present invention comprising;
a frame including a base connected through stays to the frame so as to be positioned at the central portion of the frame,
a cylindrical bearing holder formed integrally with the base to extend therefrom forwardly,
a stator including an iron core and a coil and mounted on the exterior of the cylindrical bearing holder,
an impeller including a front face plate, a flange formed over the outer periphery of the front face plate, and suitable number of blades provided on the outer periphery of the flange,
a yoke including a front face plate to which the front face plate of the impeller is secured, a flange formed over the outer periphery of the front face plate, a magnet mounted on the flange, and
a bearing device for supporting the central portion of the yoke through a sleeve thereof to which the central portion of the yoke is fit and secured thereto, the bearing device including;
a sleeve,
a stepped shaft including a larger diameter portion and a reduced diameter portion provided at one end thereof,
the first inner raceway groove formed at an appropriate position around the outer peripheral surface of the larger diameter portion,
the first outer raceway groove formed on an inner peripheral surface of the sleeve so as to correspond with the first inner raceway groove,
balls of the first row interposed between the first and second grooves,
an inner ring slidably fit over the reduced diameter portion,
the second inner raceway groove formed around an outer peripheral surface of the inner ring,
the second outer raceway groove formed on the inner peripheral surface of the sleeve so as to correspond with the second inner raceway groove,
balls of the second row interposed between the third and fourth grooves,
a stop ring provided around the inner periphery of the distal end of the reduced diameter portion, and
a pre-loading spring interposed between the stop ring and an end surface of the inner ring to provide a suitable amount of pre-loading force to the inner ring, wherein
the bearing device is provided within the cylindrical bearing holder so that the sleeve can be rotated around the axis of the bearing device, and the end of the shaft is secured to the base.
The blower in accordance with the fifth aspect of the present invention comprising;
a frame including a base connected through stays to the frame so as to be positioned at the central portion of the frame,
a stator including an iron core and a coil and mounted on the inner peripheral surface of a flange extending forwardly from an outer periphery of the base,
an impeller including a front face plate, a flange formed over the outer periphery of the front face plate, and suitable numbers of blades provided on the outer periphery of the flange,
a bearing device for supporting the central portion of a supporting plate mounted on the rear surface of the front face plate, the bearing device including;
a sleeve to which the central portion of the supporting plate is fit and secured,
a stepped shaft including a larger diameter portion and a reduced diameter portion provided at one end thereof,
the first inner raceway groove formed at an appropriate position around the outer peripheral surface of the larger diameter portion,
the first outer raceway groove formed on an inner peripheral surface of the sleeve so as to correspond with the first inner raceway groove,
balls of the first row interposed between the first and second grooves,
an inner ring slidably fit over the reduced diameter portion,
the second inner raceway groove formed around an outer peripheral surface of the inner ring,
the second outer raceway groove formed on the inner peripheral surface of the sleeve so as to correspond with the second inner raceway groove,
balls of the second row interposed between the second inner and outer grooves,
a stop ring provided around the inner periphery of the distal end of the reduced diameter portion, and
a pre-loading spring interposed between the stop ring and an end surface of the inner ring to provide a suitable amount of pre-loading force to the inner ring, wherein
the exterior of the sleeve of the bearing apparatus is provided with a cylindrical yoke on which a magnet corresponding to the coil of the stator is provided, and the end of the shaft is secured to the base.
In the blower in accordance with the sixth to the tenth aspect of the present invention, the balls for the first and second rows of any of the first to the fifth aspects of the present invention, are made of ceramic material.
In the blower in accordance with the eleventh to the fifteenth aspect of the present invention, the outer diameter of the inner ring of any of the first to the fifth aspects of the present invention are the same as that of the larger diameter portion of the shaft, and the diameter of the balls for the first row is the same as that of the balls for the second row.